USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Diamondback Terrapin Diamondback Terrapin photo by Willem M. Roosenburg
(Photo by Willem M. Roosenburg)


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Biological Characteristics

Species Malaclemys terrapin has a light brown to black carapace that bears deep growth rings and a yellow to green plastron (Behler and King, 1979). Coloring and markings of the shells can vary considerably between individuals (Wood, 1995). The head and neck are gray, peppered with black spots. Male terrapins average 10.2-13.8 cm in length and have a longer and thicker tail than females. Females tend to be larger, 15.2-23.8 cm, and more abundant than males (Behler and King, 1979; Wood, 1995).
Status in Estuaries The diamondback terrapin is the only living turtle species found exclusively in brackish coastal marshes (Wood, 1995). Dwelling in salt-marsh estuaries, tidal flats, and lagoons behind barrier beaches, it is a highly aquatic species seen out of water for an extended period of time only when nesting (Behler and King, 1979; Wood, 1995) Females lay from 4-18 pinkish-white leathery eggs in July (Behler and King, 1979). More than one clutch may be produced per nesting season (Wood, 1995). Nests are 12.5 to 15 cm cavities dug at sandy edges of marshes and dunes above the high-tide line. Hibernation generally occurs within and below the intertidal zone of the salt marsh, singly or in groups, and lasts from November through March (Wood, 1995). The maximum life span of the terrapin is unknown (Wood, 1995).
Abundance and Range The entire range of this species is confined to the United States, where they occur from Cape Cod to Texas along the Atlantic and Gulf coasts, and are year-round residents along the margins of the estuary (Behler and King, 1979; Wood, 1995).
Site Fidelity Terrapin populations may use local habitats for short periods, and then move on to other sites (Seigel, 1993).
Ease of Census Difficult
Feeding Habits Carnivores. Food preferences are broad and include gastropods, bivalves, worms, small fish, and various crustaceans (Behler and King, 1979; Wood, 1995).

Diamondback Terrapin Contaminant Exposure Data

I.

Organochlorine Contaminants

1.

An adult female terrapin was collected in July 1995 from Purvis Creek, Georgia near the site of a former chloralkali facility (Kannan et al., 1999).  Hepatic concentrations of organochlorines were 14.5 g/g lipid weight PCB, 0.01 g/g HCB, and 0.029 g/g total chlordane isomersHCH isomers, DDT metabolites, and PCDDs/PCDFs were not detected.

2.

Female terrapins were collected from the Turtle River-Brunswick Estuary Superfund site in Georgia in 1997 (Kannan et al., 1998).  Hepatic organochlorine concentrations were 1,560 ng/g wet weight total PCBs, 1.1 ng/g HCB, <35 ng/g Σ-DDT, 3.2 ng/g Σ-chlordane, and <0.61 ng/g Σ-HCHOctachlorobiphenyls occurred at the highest mean concentration of the PCB congeners, at 730 ng/g, with PCB 196 and 199 accounting for 250 and 200 ng/g, respectively.

II.

Cholinesterase-Inhibiting Pesticides

 

No direct exposure data available

III.

Trace Elements, Metals, and Metalloids

1.

Adult female diamondback terrapins (N=11) were collected along coastal New Jersey, from the south end of Barnegut Bay (Burger, 2002). Eggs (N=8) were collected if inside captured females. Concentrations of elements are expressed as arithmetic means in ng/g wet weight, SE. Egg: As 126, Cd 0.260.24, Cr 390255, Pb 4030, Mn 248141, Hg 3510, Se 49825. Liver: As 562168, Cd 6619, Cr 696, Pb 9021, Mn 2750801, Hg 1139473, Se 1621260. Muscle: As 728190, Cd 187, Cr 29740, Pb 6213, Mn 665143, Hg 17238, Se 507116.

IV.

Petroleum Crude Oil

 

No data available

V.

Other

1.

A diamondback terrapin collected from a brackish area in Florida had an observed level of radioactivity of 0.5 picocuries/gram of bone ash after analysis of the exoskeletal burden of strontium-90 (Jackson et al., 1974).

2.

Five adult female terrapins were collected in July 1995 from Purvis Creek, Georgia near the site of a former chloralkali facility (Kannan et al., 1999).  Concentrations of organohalogens--extractable organic chlorine (EOCl), extractable organic bromine (EOBr), and extractable organic iodine (EOI)--were measured in liver.  EOCl ranged from 23-58 g/g wet weight, EOBr from 0.49-3.7 g/g, and EOI from 0.10-0.22 g/g.  Values of EOBr and EOI were higher in terrapins than birds and invertebrates collected from the same location.

Diamondback Terrapin Contaminant Response Data

I.

Organochlorine Contaminants

1.

Treatments of DDT (up to 1.6 lb/acre) and BHC (0.2 lb/acre) on tidal marshes near the Brigantine National Wildlife Refuge in Oceanville, New Jersey, from 1949-52, appeared to have no effect on diamondback terrapins present in the study areas, based on gross observations in the field (Springer, 1961).

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available

III.

Trace Elements, Metals, and Metalloids

 

 No response data available

IV.

Petroleum Crude Oil

 

No response data available

References for Diamondback Terrapin

Behler, J.L., and F.W. King. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, New York. 743 pp.

Burger, J. 2002. Metals in tissues of diamondback terrapin from New Jersey. Environ. Monitor. Assess. 77:255-263.

Jackson, Jr., C.G., C.M. Holcomb, S. Kleinbergs-Krisans, and M.M. Jackson. 1974. Variation in strontium-90 exoskeletal burdens of turtles (Reptilia: Testudines) in southeastern United States. Herpetologica 30:406-409.

Kannan K., H. Nakata, R. Stafford, G. R. Masson, S. Tanabe, and J.P. Giesy.  1998. Bioaccumulation and toxic potential of extremely hydrophobic polychlorinated biphenyl congeners in biota collected at a Superfund site contaminated with Aroclor 1268. Environ. Sci. Tech. 32:1214-1221.

Kannan K., M. Kawano, Y. Kashima, M. Matsui, and J.P. Giesy. 1999.  Extractable organohalogens (EOX) in sediment and biota collected at an estuarine marsh near a former chloralkali facility.  Environ. Sci. Tech. 33:1004-1008.

Seigel, R.A. 1993. Apparent long-term decline in diamondback terrapin populations at the Kennedy Space Center, Florida. Herpetol. Rev. 24:102-103.

Springer, P.F. 1961. The effects on wildlife of applications of DDT and other insecticides for larval mosquito control in tidal marshes of the eastern United States. Ph.D. Thesis. Cornell University, Ithaca, New York.

Wood, R. 1995. Diamondback terrapin. In L. E. Dove and R. M. Nyman, eds., Living Resources of the Delaware Estuary. Delaware Estuary Program pp. 299-304.

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